Buggy code:
private static final int FLAG_ENABLED = 128 ; private static final int FLAG_IS_RENDERED_ONCE = 4096 ; private static final int FLAG_IS_RENDER_ALLOWED = 8192 ; private static final int FLAG_OUTPUT_MARKUP_ID = 16384 ; private static final int FLAG_PLACEHOLDER = 32768 ; protected static final int FLAG_RESERVED1 = 256 ; protected static final int FLAG_RESERVED2 = 512 ; protected static final int FLAG_RESERVED3 = 1024 ; protected static final int FLAG_RESERVED4 = 2048 ; protected static final int FLAG_RESERVED5 = 65536 ; protected static final int FLAG_RESERVED6 = 131072 ; protected static final int FLAG_RESERVED7 = 262144 ; protected static final int FLAG_RESERVED8 = 524288 ; static final int FLAG_ATTACH_SUPER_CALL_VERIFIED = 268435456 ; static final int FLAG_ATTACHED = 536870912 ; static final int FLAG_ATTACHING = 1073741824 ; private static final int FLAG_DETACHING = - 2147483648 ; private static final int FLAG_BEFORE_RENDERING_SUPER_CALL_VERIFIED = 16777216 ; private static final int FLAG_RENDERING = 33554432 ; private static final int FLAG_AFTER_RENDERING = 134217728 ; private static final MetaDataKey BORDER_KEY = new MetaDataKey ( IComponentBorder . class ) { private static final long serialVersionUID = 1L ; } ; static final MetaDataKey CONSTRUCTED_AT_KEY = new MetaDataKey ( String . class ) { private static final long serialVersionUID = 1L ; } ; static final MetaDataKey ADDED_AT_KEY = new MetaDataKey ( String . class ) { private static final long serialVersionUID = 1L ; } ; private static final IModelComparator defaultModelComparator = new IModelComparator ( ) { private static final long serialVersionUID = 1L ; public boolean compare ( Component component , Object b ) { } } ; private static final Logger log = LoggerFactory . getLogger ( Component . class ) ; private static final String MARKUP_ID_ATTR_NAME = "id" ; private static final long serialVersionUID = 1L ; private ArrayList behaviors = null ; private int flags = ( ( ( ( Component . FLAG_VISIBLE ) | ( Component . FLAG_ESCAPE_MODEL_STRINGS ) ) | ( Component . FLAG_VERSIONED ) ) | ( Component . FLAG_ENABLED ) ) | ( Component . FLAG_IS_RENDER_ALLOWED ) ; private String id ; private MetaDataEntry [ ] metaData ; IModel model ; private MarkupContainer parent ; int markupIndex = - 1 ; public Component ( final String id ) { } public Component ( final String id , final IModel model ) { } public Component add ( final IBehavior behavior ) { } public Component remove ( final IBehavior behavior ) { } public final boolean continueToOriginalDestination ( ) { } public final void debug ( final String message ) { } public void detachModels ( ) { } public final void error ( final Serializable message ) { } public final void fatal ( final String message ) { } public final MarkupContainer findParent ( final Class c ) { } public final MarkupContainer findParentWithAssociatedMarkup ( ) { } public final Application getApplication ( ) { } public final List getBehaviors ( ) { } public final String getClassRelativePath ( ) { } public final IConverter getConverter ( ) { } public IConverter getConverter ( Class type ) { } public final boolean getEscapeModelStrings ( ) { } public final FeedbackMessage getFeedbackMessage ( ) { } public String getId ( ) { } public Locale getLocale ( ) { } public final Localizer getLocalizer ( ) { } public final ValueMap getMarkupAttributes ( ) { } public String getMarkupId ( ) { } final boolean hasMarkupIdMetaData ( ) { } final void setMarkupIdMetaData ( String markupId ) { } public final Serializable getMetaData ( final MetaDataKey key ) { } public final IModel getModel ( ) { } public final Object getModelObject ( ) { } public final String getModelObjectAsString ( ) { final Object modelObject = getModelObject ( ) ; if ( modelObject != null ) { final IConverter converter = getConverter ( modelObject . getClass ( ) ) ; final String modelString = converter . convertToString ( modelObject , getLocale ( ) ) ; if ( modelString != null ) { if ( getFlag ( Component . FLAG_ESCAPE_MODEL_STRINGS ) ) { <START_BUG> return org . apache . wicket . util . string . Strings . escapeMarkup ( modelString ) . toString ( ) ; <END_BUG> } return modelString ; } } return "" ; } public final Page getPage ( ) { } public final IPageFactory getPageFactory ( ) { } public final String getPageRelativePath ( ) { } public final MarkupContainer getParent ( ) { } public final String getPath ( ) { } public final boolean getRenderBodyOnly ( ) { } public final Request getRequest ( ) { } public final RequestCycle getRequestCycle ( ) { } public final Response getResponse ( ) { } public final Session getSession ( ) { } public long getSizeInBytes ( ) { } public final String getString ( final String key ) { } public final String getString ( final String key , final IModel model ) { } public final String getString ( final String key , final IModel model , final String defaultValue ) { } public final String getStyle ( ) { } public String getVariation ( ) { } public final boolean hasErrorMessage ( ) { } public final boolean hasFeedbackMessage ( ) { } public final void info ( final String message ) { } public final boolean isActionAuthorized ( Action action ) { } public final boolean isAncestorOf ( final Component component ) { } public final boolean isEnableAllowed ( ) { } public boolean isEnabled ( ) { } public boolean isVersioned ( ) { } public boolean isVisible ( ) { } public final boolean isVisibleInHierarchy ( ) { } public final void modelChanged ( ) { } public final void modelChanging ( ) { } public final Page newPage ( final Class c ) { } public final Page newPage ( final Class c , final PageParameters parameters ) { } public final void redirectToInterceptPage ( final Page page ) { }

Fix:
return org . apache . wicket . util . string . Strings . escapeMarkup ( modelString , false , true ) . toString ( ) ;